The following example is an ASP.NET page that sets the Filter property to a new instance of the UpperCaseFilter class, a custom Stream class that converts all text that passes through it to uppercase. The information about the request is saved to a text file, and then the Filter property is set. After the response filter is in place, the code calls the MapPath method to get the absolute path to a text file named TestFile.txt that serves as the source for the content of the response. The code then creates a new StreamReader object to read the text file from beginning to end, and then calls the Write method to display the content of the file on the page.